1. Field of the Invention
The invention generally relates to pointing devices used with computer systems, and more particularly, to a trackball for use with portable computers and capable of being embedded in portions of the computer.
2. Description of the Related Art
The tremendous growth of the computer industry in recent years has been accompanied by advances in both computer hardware and software. Computers have become more convenient to use and so affordable that many individuals now own personal computers. As computer systems have developed to become more accessible to personal users, software has also evolved into complex programs that are simple for a relatively untrained user to operate. To maximize user comfort and familiarity, much of the current software is graphics oriented, using icons and pointers to allow the user to choose a desired application.
Pointing devices provide a simple interface between users and graphics oriented applications, allowing the user to indicate what he wants by merely pointing to it on the display. A user can initiate a program by simply moving the cursor to the desired option and pressing a select button. As the program runs, it provides the user with more options represented on the display of the computer, and the user directs the execution of the program using the pointing device.
For desktop computers, a mouse is the most common pointing device, as it is reliable and easy to use. A mouse is a device moved about a flat surface while the cursor on the display follows the movement of the mouse. In many mice a ball located on the bottom of the unit is in contact with the desktop or a mouse pad and rolls when the mouse is moved. This rolling is converted into X and Y values and provided to the computer. In addition, mice have one, two or three buttons for indicating user selection. The buttons are typically located on the top side of the mouse.
Other pointing devices include trackballs, which are essentially mice with the ball and buttons facing upward; digitizing pads; force sensitive keys; and touch screens. Most of these items are generally not integral parts of the computer, but are made by other manufacturers to be used in conjunction with the computer system. As a result, most pointing devices comprise separate units apart from the computer system.
Consequently, a mouse or other common pointing device is not particularly well suited to a portable computer. Powerful systems are now available in portable units no larger than a thick notebook and can operate in almost any environment. But for portable systems, such as laptop and notebook computers, any extra equipment that has to be carried with the computer decreases the system's portability. Ideally, the user would only have to transport the computer itself. A conventional mouse, however, is a relatively large device, employs a long cord, requires a surface on which to roll, and is not an integrated part of the computer. Other pointing devices share these and other problems.
The shortcomings of pointing devices in a portable system have usually been addressed by using trackball devices. The device's size has been reduced and the cable shortened to improve the device's compatibility with a portable system. To use the device, it is usually attached to the side of the computer case next to the keyboard, and plugged into a connector at the back of the computer during operation. The size of these devices has been reduced. Although these improvements are helpful, they only reduce the problems associated with a mouse or trackball without eliminating them. A smaller mouse with a shorter cord still needs a relatively wide, flat area to operate, and a trackball clamped to the side of the computer remains a hindrance that must be carried with the computer and generally disconnected for travel.
Several computer systems used embedded pointing devices. Computer keyboards are available which use a miniature trackball mounted in one corner, with the trackball and the buttons facing upwardly. Another keyboard embedded pointing device is a small touch pad located at one end of the keyboard. In its Powerbook series of laptop computers, Apple Corporation has mounted a trackball and two arc-shaped buttons below the space bar on the keyboard. An alternative design used in some portable computers is the Isopoint (TM) unit. The Isopoint design is basically a cylinder which rotates axially and slides longitudinally, the cylinder mounted below the space bar. Buttons flank the cylinder or the entire cylinder can be depressed. In yet another variation, one manufacturer is providing a "wobble key." One special key on the keyboard is designed so that it not only can be depressed, but also can be moved or pivoted in four directions, thus providing X and Y movement. The Apple and Isopoint designs have the problem of requiring increased space below the keyboard, an area already highly cramped in notebook computers. The wobble key requires a very complicated key and is not necessarily highly sensitive or intuitive. Conventional integrated designs also occupy relatively large amounts of space because of the ball and buttons being accessible from only one side.
Thus the known pointing devices are either too large and cumbersome for use if not integrated, require undesirably large amounts of space in integrated designs or are simply not considered sufficiently accurate and usable.